​ An investigation into the Degradation of Sodium Ion Electrolytes and their Effects on Battery Performance

Current battery research is dominated by lithium-ion technology, but the lithium based cell is neither sustainable nor environmentally responsible. A potential solution for future battery development is the chemically analogous sodium-ion cell. Although most research in this area has focused on the electrode materials, the electrolyte serves a critical—yet understudied—purpose in the sodium-ion battery. This research is aimed at understanding the electrochemical behavior of the sodium electrolyte in search of building a better battery. An electrolyte consisting of a sodium hexafluorophosphate (NaPF6) salt and different mixtures of solvents (cyclic and acyclic carbonates) was utilized as a base study of degradation. Various additives were utilized to hinder the degradation of the electrolyte to improve the performance and safety of the cells. Using fluoroethylene carbonate (FEC) to stabilize the solid electrolyte interface and triethoxy trifluoroethoxy phosphazene (FM2) to remove damaging hydrofluoric acid, nuclear magnetic resonance (NMR) and electrochemical cycling show here the impact on performance of the additives in multiple metrics